Fiber array with wick-stop trench for improved fiber positioning

ABSTRACT

A V-groove chip for fiber arrays having a wick stop trench. The wick stop trench intersects the V-grooves and is preferably deeper than the V-grooves. The wick stop trench prevents adhesive from moving via capillary action along the entire length of a V-groove. This is very useful for manufacturing V-groove fiber arrays because often it is desirable to adhesive the fiber to the V-groove chip in multiple gluing steps. For example, two gluing steps are beneficial if rotational alignment of the fiber (e.g., for polarization maintaining fiber arrays) is desired. Also, if longitudinal alignment of the fiber is desired, two gluing steps are beneficial. Two gluing steps allows the front and rear portions of the optical fiber to be secured independently, thereby improving precision in fiber placement. Preferably, the wick stop trench is filled with solidified adhesive.

RELATED APPLICATIONS

[0001] The present patent application is a continuation-in-part ofcopending parent patent application 09/526,922, filed on Mar. 16, 2000.The present application claims the benefit of priority of the parentapplication.

FIELD OF THE INVENTION

[0002] The present invention relates generally to optical fiber arraysand micromachined chips used in optical fiber arrays. More specifically,it relates to a V-groove chip having a wick stop trench to prevent theuncontrolled wicking and movement of adhesive during manufacture of aV-groove fiber array.

BACKGROUND OF THE INVENTION

[0003] Micromachined V-groove chips are commonly used in the opticalfiber industry and photonics industry to align and position opticalfibers. Typically, V-groove fiber arrays are made by placing opticalfibers in V-grooves of a V-groove chip, placing a lid on the fibers, andthen securing the assembly with adhesive. The lid can be a V-groove chipor a flat silicon or glass plate. The adhesive is typically a UV-curableor heat-curable epoxy.

[0004] The optical fibers must be carefully located in the V-groovesduring manufacture of the array. Specifically, the optical fibers mustbe disposed in contact with the surfaces of the V-grooves. Also, forfiber arrays having polarization-maintaining fiber, the optical fibersmust have an accurate rotational alignment. Also, some fiber arrays needto have optical fibers placed so that the fiber endfaces are fixed atdifferent longitudinal positions.

[0005] It can be difficult to position optical fibers in conventionalV-groove chips. This is because adhesive used to secure the fibers wicksby capillary action into the small spaces between the fibers andV-grooves. Since the adhesive wicks into these spaces, the entire lengthof the fiber is secured to the V-groove chip in a single step. It is notpossible to secure the fiber in the V-groove in multiple gluing steps.This is a problem for certain fiber arrays because multiple gluing stepscan improve the alignment of optical fibers.

[0006] U.S. Pat. No. 5,257,332 to Pimpinella discloses a fiber couplerhaving V-groove chips.

[0007] U.S. Pat. No. 5,748,822 to Miura et al. discloses a module forconnecting an optical fiber to an optical element such as a laser diode.The module has a vertical groove cut perpendicular to the V-grooves. Thevertical groove is positioned to abut the fiber endface and providelongitudinal positioning of the optical fiber.

OBJECTS AND ADVANTAGES OF THE INVENTION

[0008] Accordingly, it is a primary object of the present invention toprovide a V-groove chip that:

[0009] 1) controls wicking of adhesive so that optical fibers can beglued in multiple gluing steps;

[0010] 2) provides for improved alignment of optical fibers in aV-groove chip;

[0011] 3) provides for improved longitudinal alignment of opticalfibers;

[0012] 4) provides for improved rotational alignment optical fibers.

[0013] These and other objects and advantages will be apparent uponreading the following description and accompanying drawings.

SUMMARY OF THE INVENTION

[0014] These objects and advantages are attained by a V-groove chiphaving a wick stop trench. The wick stop trench intersects the V-groove.An optical fiber is disposed in the V-groove and crosses over the wickstop trench. The wick stop trench is filled with adhesive. The wick stoptrench prevents adhesive from moving via capillary action along theentire length of the V-groove. This provides increased control overadhesive application and placement of the fiber in the V-groove.Preferably, the wick stop trench is deeper than the V-groove.

[0015] Preferably, the wick stop trench has vertical sidewalls. Also,the trench can be cut using a dicing saw.

[0016] The trench can have a width of about 20-500 microns or wider.More preferably the width is in the range of 100-200 microns. The wickstop trench can even be 1-5 mm wide if desired.

[0017] Preferably, the trench is perpendicular to the V-groove.

[0018] Also preferably, the trench divides the V-groove into groovesections of equal length. Preferably, the groove sections are at least200 or 1000 microns long. Alternatively, the groove sections can be 10,50, or 100 microns long.

[0019] The present invention includes a method for making a fiber arrayhaving a wick stop trench. In this method, an optical fiber is disposedin the V-groove. The fiber is glued to front and rear groove sections inseparate gluing steps. Optionally, different adhesives are used ingluing the front and rear groove sections. Also, rotational orlongitudinal alignment can be provided for the fiber before the fiber isglued to the front groove section. In a final step, the wick stop trenchis filled with adhesive, and the adhesive is cured.

DESCRIPTION OF THE FIGURES

[0020]FIG. 1 is a V-groove chip according to the present invention.

[0021]FIG. 2 is a side view of a V-groove chip of the present invention.

[0022]FIGS. 3a-b are side views of V-groove arrays of the presentinvention.

[0023]FIGS. 4a-b illustrate a preferred method for making the presentinvention.

[0024]FIGS. 5a-d illustrate a preferred method of the present invention.

[0025]FIG. 6 is a top view illustrating longitudinal positioningaccording to the present invention.

[0026]FIG. 7 is a side view of a V-groove chip having two wick stoptrenches.

[0027]FIG. 8 is a top view of an embodiment where the wick stop trenchis not perpendicular to the V-grooves.

[0028]FIG. 9 shows a side view of the present fiber array having afilled wick stop trench.

[0029]FIGS. 10a-10 b illustrate a preferred method for making thepresent fiber array with a filled wick stop trench.

[0030]FIG. 11 shows a close-up side view of the wick stop trench,illustrating a fillet boundary.

[0031]FIG. 12 shows a close-up side view of the wick stop trench,illustrating a fillet boundary that extends to the bottom of the wickstop trench.

[0032]FIG. 13 shows a close-up side view of a fiber array having twofillets created by separate adhesive applications to the front groovesection and rear groove section.

[0033]FIG. 14 show a clasp side view of a fiber array with a fillet wickstop trench and two fillet boundaries. The fiber array of FIG. 14 ismade by filling the wick stop trench of the fiber array of FIG. 13.

DETAILED DESCRIPTION

[0034] A V-groove chip according to the present invention has a wickstop trench that prevents adhesive from wicking the entire length of aV-groove. The wick stop trench is perpendicular to the V-groove andpreferably deeper than the V-groove. The wick stop trench divides theV-groove into groove sections which can be glued separately in distinctgluing steps. The ability to secure a fiber in multiple gluing stepsfacilitates improved fiber positioning. The present invention isparticularly well suited for accurate longitudinal and rotationalpositioning of an optical fiber in a V-groove.

[0035]FIG. 1 shows a V-groove chip according to a preferred embodimentof the present invention. The V-groove chip has a substrate 20 with atop surface 22. V-grooves 24 a-f are disposed in the substrate 20. Awick stop trench 26 intersects the V-grooves 24 a-f. Groove sections 24a-b are aligned across the wick stop trench 26 and in the presentapplication are considered to comprise a single V-groove. Similarly,groove sections 24 c-d and 24 e-f are aligned and considered to comprisesingle V-grooves.

[0036] V-groove sections 24 a-f are aligned in a longitudinal direction28, and the wick stop trench 26 is aligned in a transverse direction 30.Preferably, the wick stop trench 26 is perpendicular to the V-grooves 24a-f.

[0037] Also preferably, the substrate 20 is made of single crystalsilicon, and the top surface 22 is aligned with the <100>crystal plane.V-grooves 24 a-f are preferably made by wet anisotropic orientationdependent etching (e.g. using KOH) as is known in the art of siliconmicromachining. The wick stop trench 26 is preferably made by a dicingsaw, and can have a wide range of depths and widths. The wick stoptrench 26 is preferably deeper than the V-grooves 24 a-f. Alternatively,the wick stop can be made by any other micromachining technique (e.g.reactive ion etching is a possibility). The location and dimensions ofthe wick stop trench do not need to be precisely defined.

[0038] It is noted that V-groove chips are sometimes made from quartz orsimilar materials with V-grooves formed by grinding. The presentinvention is equally applicable to such V-groove chips.

[0039]FIG. 2 shows a side view of the wick stop trench 26. Dotted lines32 indicate the bottom corners of the V-grooves 24 a-f. The wick stoptrench has sidewalls 38. In some embodiments, the sidewalls 38 arevertical (i.e. perpendicular to the top surface). The sidewalls 38 arevertical in embodiments where the trench is made using a dicing saw. Thewick stop trench 26 has a width 34 and a depth 36. As noted, the wickstop trench is preferably deeper than the V-grooves (i.e. deeper thanthe dotted lines 32). The wick stop trench may be slightly deeper thanthe V-grooves (e.g. 50, 100, or 200 microns deeper than the V-grooves);the wick stop trench may also be slightly shallower than the V-grooves(e.g. 5, 10, or 20 microns shallower. In either case, the wick stoptrench must be deep enough to stop capillary action of adhesive betweenthe V-groove and a fiber disposed in the V-groove. The required depthmay depend on the size of the optical fiber, the viscosity of theadhesive, and the wetting properties of the chip, optical fiber andadhesive.

[0040] The trench width 34 can be in the range of 20-500 microns.Preferably, the width 34 is about 150 microns, or in the range of100-200 microns. The trench width should be kept relatively short toprevent microbending of an optical fiber in the V-groove. The trench canbe relatively wide (e.g. 1-3 millimeters) although this is notpreferred.

[0041] Preferably, the wick stop trench 26 is centered on a midpoint 39of the V-grooves so that the V-grooves are divided into sections 40 ofequal length. Alternatively, the wick stop trench 26 is located off themidpoint 39 so that the V-grooves are divided into unequal lengths. Inthis case, each section of the V-grooves should be at least 50-200-500microns long. More preferably, each length is at least 2-4 millimeterslong.

[0042]FIG. 3a shows a side view of an optical fiber array according tothe present invention. An optical fiber 42 is disposed in the V-groove24. Dotted line 32 indicates the bottom of the V-groove 24. A lid 44 isdisposed on top of the optical fiber and holds the fiber 42 in theV-groove. The lid 44 can be made of glass, silica or silicon, forexample. The wick stop trench 26 may be filled with adhesive, or may beempty. Also, the lid 44 can be replaced with a V-groove chip (with orwithout a wick stop trench). A front face 47 of the array is preferablypolished for optical connection to other optical components.

[0043]FIG. 3b shows an alternative embodiment where the lid 44 onlycovers one front length 45 of the V-groove. This embodiment may beuseful if hardened adhesive residue 43 is adhered to the optical fiber42 because such adhesive residue can prevent the proper placement of thelid.

[0044]FIGS. 4a-b illustrate a method for making the chips of the presentinvention. In FIG. 4a, a V-groove 24 is formed in a single crystalsilicon substrate 20 using wet anisotropic etching. Optionally, arecessed area 46 for bonding coated fibers is etched to a level asdeeper than the V-grooves. Next, in FIG. 4b, the wick stop trench 26 iscut across the V-groove 24, dividing the V-groove into front groovesection 24 t and rear groove section 24 k. Groove sections 24 k and 24 tcan be equal or unequal in length. Preferably, the trench 26 is cutusing a dicing saw or similar device. Preferably, a large number ofV-groove chips are cut with the dicing saw while still connected inwafer form.

[0045]FIGS. 5a-5 c illustrate a preferred method of the presentinvention for securing an optical fiber in a V-groove chip according tothe present invention. First, in FIG. 5a, the optical fiber 42 isdisposed in the front 24 t and rear 24 k V-groove sections. Therotational alignment of the fiber may be adjusted, and the longitudinalalignment of the fiber may be adjusted. Next, in FIG. 5b, adhesive 48(e.g. UV curable epoxy) is disposed in the rear groove section 24 k. Theadhesive 48 travels by capillary action (wicking) along the rear groovesection 24 k and stops at the wick stop trench 26. The adhesive maypartially fill the wick stop trench 26. The adhesive does not travel tothe front groove section 24 t because of the wick stop trench 26. Next,the adhesive in the rear groove section 24 k is hardened using UVillumination. Hardening the adhesive 48 secures the rotational andlongitudinal alignment of the optical fiber 42. At this point, the fiber42 is not attached to the front groove section 24 t.

[0046] It is noted that the fiber may not be accurately disposed in thefront groove section 24 t during or after adhesive 48 is set in the reargroove section 24 k. This is because the fiber 42 is not pressed intothe front groove section 24 t. FIG. 5c illustrate a possiblemispositioning of the fiber in the front groove section 24 t.

[0047] Next, in FIG. 5d, a lid 44 is placed on top of the fiber 42. Inthe embodiment shown, the lid 44 only covers the front groove sectionand does not cover the rear groove section 24 k. Placement of the lidpresses the optical fiber into the front groove section 24 t therebyproviding accurate positioning of the fiber. The rotational andlongitudinal alignment of the fiber is fixed by the adhesive 48 in therear groove section before the lid is placed. After the lid is placed,adhesive is disposed in the front groove section 24 t from either thewick stop trench 26 or the front face 47 and hardened using UVillumination. Since the rotational/longitudinal alignment and positionof the fiber with in the V-groove are set independently in two separategluing steps, each alignment can be done with higher precision. In theprior art, rotational/longitudinal alignment and pressing of the fiberinto the groove must be performed in the same gluing step.

[0048] The ability of the wick stop trench 26 to stop the adhesivetravel is an essential feature of the present invention. Since the wickstop trench can control the movement of liquid adhesive, differentportions of the optical fiber 42 can be glued in distinct gluing steps.The ability to glue different portions of the fiber in distinct stepsprovides for improved fiber alignment and other benefits in certainkinds of fiber arrays. This is because longitudinal/rotational alignmentcan be fixed in a separate step from pressing the fiber into the groove.

Example 1 Polarization-maintaining Optical Fiber Array

[0049] The present invention is particularly well suited for makingpolarization-maintaining (PM) optical fiber V-groove arrays. A methodfor making PM fiber V-groove arrays according to the present inventionincludes the following steps:

[0050] 1) Place a PM fiber in the rear groove section and front groovesection.

[0051] 2) Rotate the PM fiber until properly aligned.

[0052] 3) Apply adhesive to the rear groove section and cure theadhesive, thereby fixing the rotational alignment.

[0053] 4) Place a lid on the PM fiber and press the fiber into the frontgroove section to accurately position the fiber in the front groovesection.

[0054] 5) Apply adhesive to the front groove section and cure adhesive.

EXAMPLE 2 Optical Fiber Array with Longitudinally Located Fibers.

[0055]FIG. 6 shows an optical fiber array where the optical fibers 42a-c are located longitudinally. Endfaces 50 are not flush (coplanar)with the front face 47 of the array and substrate. A method for makingfiber V-groove arrays with longitudinally located fibers according tothe present invention includes the following steps:

[0056] 1) Place a fiber in the rear groove section and front groovesection.

[0057] 2) Longitudinally move the fiber until properly aligned.

[0058] 3) Apply adhesive to the rear groove section and cure theadhesive, thereby fixing the longitudinal alignment.

[0059] 4) Place a lid on the fiber and press the fiber into the frontgroove section to accurately position the fiber in the front groovesection.

[0060] 5) Apply adhesive to the front groove section and cure adhesive.

[0061] It is noted that a jig having fiber stops can be used tolongitudinally locate the optical fibers in this embodiment.

[0062] It is noted that the present invention can be used in anysituation where multiple gluing steps are desired. For example,different adhesives can be used in different groove sections. This maybe useful, for example, where an adhesive having good polishingproperties is used in the front groove section and a different adhesivehaving good adhesion/expansion properties is used in the rear groovesection.

[0063] It is also noted that the present invention includes embodimentshaving more than one wick stop trench. FIG. 7, for example, shows a sideview of a V-groove chip having two wick stop trenches 26 a, 26 bdividing the V-groove into three groove sections 24 x, 24 y, 24 z.

[0064] It is also noted that the wick stop trench does not need to beperpendicular to the V-groove. The wick stop trench can be located atalmost any angle provided that the wick stop prevents the wicking ofadhesive. The wick stop trench could be oriented at 60 degrees withrespect to the V-grooves, for example. FIG. 8 shows a top view of anembodiment with a nonperpendicular wick stop trench.

[0065]FIG. 9 is a side view of a fiber array made according to apreferred embodiment of the present invention. The wick stop trench isfilled (filled up to the bottom of the optical fiber) with hardenedadhesive 52. Although the wick stop trench 26 functioned as a wick stopwhen liquid adhesive was placed into the rear groove section 24 k, inthe step of adhering the fiber to the front groove section 24 t of thearray, the wick stop trench 26 is filled with adhesive. The liquidadhesive flows from the wick stop trench into the front groove section24 t. Filling the wick stop trench with adhesive simplifies the task ofadhering the front portions of the optical fibers to the front V-groovesection, and provides other benefits.

[0066]FIGS. 10a-10 b illustrate a preferred method for making the fiberarray with a filled wick stop trench. FIGS. 10a-10 b Are close-up sideviews of the wick stop trench and optical fiber and only show a portionof the V-groove chip and fiber.

[0067]FIG. 10a The optical fiber is disposed in the V-groove 24 k 24 t.Liquid adhesive (e.g. UV-curable epoxy) is applied to the rear groovesection 24 k, forming a fillet 54 due to surface tension forces. Thewick stop trench 26 prevents the liquid adhesive from flowing into thefront groove section 24 t. The liquid adhesive is cured so that thefillet 54 becomes solid. Before application and curing of the adhesivein the rear groove section 24 k, longitudinal and/or rotationalalignment of the optical fiber may be provided.

[0068]FIG. 10b The wick stop trench is filled with liquid adhesive 56.Preferably, the wick stop trench is filled completely (up to the topsurface of the V-groove chip). The liquid adhesive flows into the frontgroove section 24 t by capillary action as the wick stop trench isfilled. The adhesive in the wick stop and front groove section is thencured. A fillet boundary 58 may be present. The fillet boundary 58indicates that the two adhesive applications were solidified in separatesteps.

[0069] An adhesive-filled wick stop trench provides several distinctadvantages:

[0070] 1) A filled wick stop trench provides improved strength for theV-groove chip. If the wick stop trench is not filled, then the chip issubstantially weakened by the wick stop trench.

[0071] 2) Applying adhesive to the front groove sections by filling thewick stop trench simplifies the task of applying adhesive to the frontgroove sections. Only a single adhesive application is necessary; aseparate adhesive application is not required for each optical fiber inthe fiber array.

[0072] 3) Filling the wick stop trench reduces the occurrence of trappedair bubbles in the fiber array. Trapped air bubbles are often formed ifthe wick stop trench is not filled and a lid is glued onto the fiberarray. Trapped air bubbles are best avoided because they can causeadhesive delamination when the array is exposed to temperature cycling.

[0073] Although the fillet boundary is a preferred feature of thepresent invention, it is not essential. The present invention includes afiber array having a wick stop trench filled with adhesive.

[0074]FIG. 11 shows a magnified side view of the filled wick stop trenchhaving a fillet boundary 58 created by two separate application andsolidification steps. The fillet boundary will be readily apparent ifdifferent adhesives are used in the front and rear groove sections. Ifthe same adhesive is used in the front and rear groove sections, thefillet boundary may be difficult to observe. An optical fiber array madeaccording to the preferred method of the present invention will have afillet boundary, although the fillet boundary may be difficult toobserve.

[0075]FIG. 12 shows an alternative embodiment where the fillet boundaryextends to the bottom of the wick stop trench. In this embodiment, thebottom of the wick stop trench was partially wetted by the firstadhesive application.

[0076]FIG. 13 shows another embodiment of the present invention whereboth the front groove section 24 t and rear groove section 24 k arefilled with liquid adhesive so that two fillets 54, 60 are formed. Theembodiment of FIG. 13 is made by applying liquid adhesive to the frontgroove section instead of the wick stop trench.

[0077]FIG. 14 shows yet another embodiment where the wick stop trench ofthe fiber array of FIG. 13 is filled with liquid adhesive 61 (in a thirdadhesive application). The fiber array of FIG. 14 has two filletboundaries 58, 62.

[0078] It is noted that a fiber array made according to the method ofthe present invention will have a fillet boundary.

[0079] It is further noted that the V-groove does not necessarily have apointed, V-shaped bottom. The V-groove can have a flat bottom. V-grooveswith flat bottoms are commonly used in the art and are readily made insilicon using wet anisotropic etching techniques.

[0080] Although the present invention has been described with referenceto using V-grooves, the present invention can be used with grooves ofany cross sectional shape. For example, the present invention can beused with grooves having U-shapes or rectangular shapes. Also, the wickstop trench can have essentially any shape (e.g. V-shaped, U-shaped),provided that it functions as a wick stop.

[0081] Also, the V-groove chips of the present invention can be made ofmaterials other than silicon including ceramic, quartz, plastic andmetal.

[0082] It will be clear to one skilled in the art that the aboveembodiment may be altered in many ways without departing from the scopeof the invention. Accordingly, the scope of the invention should bedetermined by the following claims and their legal equivalents.

What is claimed is:
 1. An optical fiber array, comprising: a) asubstrate having a top surface; b) a groove disposed in the top surface;c) a wick stop trench intersecting the groove so that the groove isdivided into groove sections; d) an optical fiber disposed in the groovesections and crossing the wick stop trench; e) solidified adhesivefilling the wick stop trench.
 2. The optical fiber array of claim 1wherein the solidified adhesive has a fillet boundary.
 3. The opticalfiber array of claim 2 wherein the fillet boundary extends to the bottomof the wick stop trench.
 4. The optical fiber array of claim 1 whereinthe wick stop trench is deeper than the groove.
 5. The optical fiberarray of claim 1 wherein the substrate is made of single crystal siliconand the groove is a crystallographically defined V-groove.
 6. Theoptical fiber array of claim 1 wherein the wick stop trench has verticalsidewalls.
 7. The optical fiber array of claim 1 wherein the wick stoptrench is a dicing saw cut trench.
 8. The optical fiber array of claim 1wherein the wick stop trench has a width in the range of 20-500 microns.9. The optical fiber array of claim 1 wherein the wick stop trench has awidth in the range of 100-200 microns.
 10. The optical fiber array ofclaim 1 further comprising a second wick stop trench so that the grooveis divided into three groove sections, and wherein the second wick stoptrench is filled with solidified adhesive.
 11. The optical fiber arrayof claim 1 wherein the wick stop trench intersects a midpoint of thegroove so that the groove is divided into two equal-length groovesections.
 12. The optical fiber array of claim 1 wherein the groovesections are at least 200 microns long.
 13. The optical fiber array ofclaim 1 wherein the groove sections are at least 1000 microns long. 14.The optical fiber array of claim 1 wherein the optical fiber is apolarization maintaining optical fiber.
 15. The optical fiber array ofclaim 1 wherein the optical fiber has a fiber endface, and wherein thesubstrate has a front face, and wherein the fiber endface is notcoplanar with the substrate front face.
 16. The optical fiber array ofclaim 1 wherein the solidified adhesive comprises two fillet boundariesadjacent to the front and rear groove sections.
 17. A method for makingan optical fiber array, comprising the steps of: a) providing a groovechip having a wick stop trench and a groove, wherein the groove isdivided by the trench into a front groove section and a rear groovesection; b) disposing an optical fiber in the front and rear groovesections so that it crosses the trench; c) applying liquid adhesive tothe rear groove section so that the liquid adhesive flows along theoptical fiber up to the wick stop trench and forms a fillet; d) curingthe adhesive applied in step (c); e) after step (d), filling the wickstop trench with adhesive so that the liquid adhesive flows into thefront groove section; f) curing the adhesive applied in step (e)
 18. Themethod of claim 17 wherein different adhesives are used in steps (c) and(e).
 19. The method of claim 17 further comprising the step of providingrotational alignment of the optical fiber before step (d).
 20. Themethod of claim 17 further comprising the step of providing longitudinalalignment of the optical fiber before step (d).
 21. An optical fiberarray made according to the method of claim 17 so that the fiber arrayhas a fillet boundary.
 22. A method for making an optical fiber array,comprising the steps of: a) providing a groove chip having a wick stoptrench and a groove divided into a front groove section, wherein thegroove is divided by the trench into a front groove section and a reargroove section; b) disposing an optical fiber in the front and reargroove sections so that it crosses the trench; c) applying liquidadhesive to the rear groove section so that the liquid adhesive flowsalong the optical fiber up to the wick stop trench and forms a fillet;d) curing the adhesive applied in step (c); e) applying liquid adhesiveto the front groove section so that the liquid adhesive flows along theoptical fiber up to the wick stop trench and forms a second fillet; f)curing the adhesive applied in step (e); g) after step (f), filling thewick stop trench with adhesive; h) curing the adhesive applied in step(g).
 23. The method of claim 16 wherein different adhesives are used insteps (c) and (e).
 24. The method of claim 16 further comprising thestep of providing rotational alignment of the optical fiber before step(d).
 25. The method of claim 16 further comprising the step of providinglongitudinal alignment of the optical fiber before step (d).
 26. Anoptical fiber array made according to the method of claim 22 so that thefiber array has two fillet boundaries.